The present invention relates to trenching machines and, more particularly, to hand-operated trenching machines. It is to be appreciated, however, that the invention is not limited thereto.
Trenching machines of the form addressed by the present invention are designed primarily for digging trenches in the ground. Applications for such trenches include the installation of pipes, drains, cables, and the like. Such trenches are typically relatively shallow.
Difficulties exist in removing the digging implement of existing trenching machines, which are generally in the form of chain-mounted digging teeth.
Moreover, the manoeuvrability of existing trenching machines has generally been found to be less than desirable, particularly when used for applications requiring relatively tight cornering of the machine.
Furthermore, existing machines generally undesirably experience a temporary reduction in power delivered to the digging implement when raising and lowering the chain guide carrying the digging implement. This is because raising and lowering the chain guide in existing machines generally requires power to be drawn from the motor driving the machine""s digging implement.
It is an object of the present invention to address at least one of the above mentioned deficiencies of existing trenching machines.
One aspect of the present invention is directed to addressing the problem of manoeuvrability of existing trenching machines.
According to one aspect of the present invention there is provided a trenching machine including:
a wheeled frame,
a first motor means on the frame,
the first motor means driving a digging chain carried on a chain guide extending from the machine,
the chain guide being pivotally mounted coaxially with a drive chain drive sprocket,
means for pivotally moving the chain guide relative to the frame,
locking means to lock the chain guide in a desired pivotal position, and
a second motor means on the frame,
the second motor means driving at least one of the machine wheels for moving the machine along the ground,
wherein the second motor means is releasably engaged to the at least one of the machine wheels.
In a preferred embodiment of the invention, the frame is mounted on four wheels to support the machine for movement along the ground. However, it is to be appreciated that the frame could be mounted on any number of wheels.
It is to be appreciated that the second motor means could drive any number of the frame wheels. In this respect, the second motor means could be arranged to drive only one of the frame wheels. Alternatively, the second motor means could be arranged to drive each of the frame wheels.
In one particularly preferred form the second motor means drives at least two of the frame wheels.
Preferably the at least two frame wheels are arranged in a substantially coaxial manner on the frame.
Preferably, the at least two substantially coaxially arranged wheels (hereinafter referred to as drive wheels) are independently rotatable when the second motor means is disengaged from the drive wheels; and are rotated in unison when the second motor means is engaged with the drive wheels.
In one preferred form there is provided at least two coaxial drive pulleys, and corresponding coaxial driven pulleys, with a belt extending around each respective drive pulley/driven pulley combination. The drive pulleys are connected to a common shaft, which is rotated by the second motor means. The driven pulleys are connected to separately rotatable coaxial shafts, which drive respective drive wheels.
When sufficient tension is maintained in the belts and the second motor means is activated, the second motor means drives the drive pulleys, causing the driven pulleys to rotate in unison. Rotation of the driven pulleys, in turn, causes the drive wheels to rotate in unison to move the machine. When it is desired to change the machine direction, the belts are loosened to the point where the driven pulleys are able to rotate independently of the drive pulleys and therefore also independently of one another. This enables the drive wheels to be rotated independently of one another, thereby enabling the user to manoeuvre the machine as desired.
Preferably the belts are adjustably tensioned via an adjustable tension pulley or pulleys.
In a preferred form, the tension pulley(s) are caused to tension the belts via a hand-operated lever.
The invention has so far been described as including a first motor means and a second motor means. It is to be appreciated, however, that the first motor means and the second motor means could be the same motor means. That is, the same motor means could be used for driving the digging chain carried on a chain guide extending from the machine, and for driving the at least one machine wheel for moving the machine along the ground.
Also, it is to be appreciated that the frame wheels could be replaced by, or used in conjunction with, any other suitable form including caterpillar-type endless track assembly arrangements, if desired.
Preferably, the machine includes handles at one end for guiding movement of the machine along the ground.
A further aspect of the present invention is directed to addressing the difficulties in removing and fitting the digging implement of existing trenching machines.
According to another aspect of the present invention, there is provided a trenching machine including:
a wheeled frame,
a first motor means on the frame,
the first motor means driving a digging chain carried on a chain guide extending from the machine,
the chain guide being pivotally mounted coaxially with a drive chain drive sprocket,
means for pivotally moving the chain guide relative to the frame,
locking means to lock the chain guide in a desired pivotal position, and
a second motor means on the frame,
the second motor means driving at least one of the machine wheels for moving the machine along the ground,
wherein the chain guide is releasably securable in a position relative to the drive chain sprocket enabling fitting and removal of the digging chain from the machine.
In a preferred form, the chain guide is longitudinally slidably mounted on a boom, with the boom being pivotally mounted to the frame coaxially with the drive sprocket. In this configuration the chain guide is slidable along the boom from a position where the digging chain is taut about the drive sprocket and chain guide, to a position where the digging chain is loosely fitted around the drive sprocket and chain guide.
In one form, apertures are provided in the chain guide and boom. The apertures are aligned when the chain guide is moved longitudinally along the boom to a point where the digging chain is loosened sufficiently to allow fitting and removal of the digging chain. A securing pin can then be releasably inserted through the aligned holes to enable fitting and/or removal of the digging chain from the machine to be undertaken.
According to another aspect of the present invention there, is provided a combination of a boom for pivotally mounting to a trenching machine, and a chain guide slidably mounted on the boom, wherein the chain guide is releasably securable to the boom in a position enabling fitting and removal of a digging chain about the chain guide.
In a preferred form, a biasing spring is provided to bias the chain guide away from the drive sprocket to thereby tension the digging chain about the drive sprocket and chain guide.
Preferably, a mechanism is provided for moving the chain guide against the force of the biasing spring, to enable the chain guide to be releasably secured to the boom in a position enabling fitting and removal of the digging chain. In one form, the mechanism includes a levering arm which, when actuated by the operator, moves the chain guide along the boom against the biasing action of the biasing spring.
A further aspect of the present invention is directed to addressing the temporary reduction in power delivered to the digging implement of existing trenching machines when raising and lowering the boom carrying the digging implement.
According to another aspect of the present invention, there is provided a trenching machine including:
a wheeled frame,
a first motor means on the frame,
the first motor means driving a digging chain carried on a chain guide extending from the machine,
the chain guide being pivotally mounted coaxially with a drive chain drive sprocket,
means for pivotally moving the chain guide relative to the frame,
locking means to lock the chain guide in a desired pivotal position, and
a second motor means on the frame,
the second motor means driving at least one of the machine wheels for moving the machine along the ground, wherein
the means for pivotally moving the chain guide relative to the frame includes
an actuating arm.
Most preferably, the actuating arm is pivotally connected between the frame and at least one of the chain guide, or a boom upon which the chain guide is slidably mounted.
In a particularly preferred form, the actuating arm includes a longitudinally movable screw threaded shaft which meshes with a rotatably mounted helical or bevel gear. Preferably, the helical or bevel gear is rotatably mounted within a housing.
The actuating arm has been described as including a screw threaded shaft and mating helical or bevel gear. However, it is to be appreciated that the actuating arm could adopt any suitable form, including that of a hydraulic ram, screw threaded shaft and mating trunnion, or other appropriate form.
In a particularly preferred form, the actuating arm includes a motor means for rotating the helical or bevel gear to longitudinally move the screw threaded shaft.
Preferably, the actuating arm motor means is in the form of an electric motor connected to an electric power source. However, it is to be appreciated that the motor means could adopt any suitable form. Indeed, it is to be appreciated that the actuating arm motor means could be actuated by the first motor means provided for driving the digging chain and/or the second motor means for moving the machine along the ground.
In a preferred embodiment, the electric power source is in the form of an electric battery mounted on the machine.
In a preferred form, the actuating arm is capable of pivotally moving the chain guide relative to the frame to at least three distinct positions. The first of these positions provides the digging chain in a digging position, with the distal end of the chain digging the ground below ground level. The second position provides the chain guide in a digging commencement position, such that the digging chain rests upon the surface of the ground. The third position provides the chain guide in a non-digging position, wherein the digging chain is clear of the ground surface.
In a preferred form, the operator activates the actuating arm by an electrically operated switch.
The present invention has so far been described in terms of a number of aspects. It is to be appreciated that a trenching machine according to the present invention could include any one or more of the above-defined aspects of the invention.
It will now be convenient to hereinafter describe the invention in greater detail by reference to the accompanying drawings, which show one embodiment of the invention. The particularity of the drawings and the associated description is not to be understood as superseding the generality of the preceding broad description of the invention.